Study does not find population-level changes in firearm homicide or suicide rates in California 10 years after comprehensive background check and violent misdemeanor policies enacted

A study of firearm homicide and suicide rates in the 10 years after California simultaneously mandated comprehensive background checks for nearly all firearm sales and a prohibition on gun purchase and possession for persons convicted of most violent misdemeanor crimes found no change in the rates of either cause of death from firearms through 2000.

The study, which posted online Oct. 12 as in press at the journal Annals of Epidemiology, was conducted by the Violence Prevention Research Program (VPRP) at UC Davis and the Johns Hopkins Bloomberg School of Public Health. It compared observed annual firearm homicide and suicide rates in California over 10 years following enactment of comprehensive background check and misdemeanor violence prohibition policies in 1991 with expected rates based on data from 32 control states that did not have these policies and did not implement other major firearm policies during the same time.

“In the 10 years after policy implementation, firearm suicide rates were, on average, 10.9 percent lower in California than expected, but we observed a similar decrease in non-firearm suicide,” said Garen Wintemute, professor of emergency medicine and director of the Violence Prevention Research Program at UC Davis, senior author on the study.

“This suggests that the policies’ estimated impact on firearm suicide may be part of broader changes in suicide risk around the time that the California policies were implemented,” he said.

The study found no net difference between firearm-related homicide rates before and during the 10 years after policy implementation.

The findings of the current study disagree with those of studies associating comprehensive background check policies with a reduction in firearm homicide and suicide in Connecticut, and an increase in firearm homicide and suicide after comprehensive background check repeal in Missouri. Connecticut has, and Missouri had, permit-to-purchase policies, however, and the permit requirement may be associated with effectiveness.

The authors believe several factors may explain the findings of the study. Leading possibilities include inadequate criminal and mental health records, incomplete compliance and the small size of the population directly affected by the laws.

“Incomplete reporting of prohibiting data to background check systems in the 1990s, prior to implementation of the policies in California, is an important limiting factor,” Wintemute said. “In 1990, only 25 percent of criminal records were accessible in the primary federal database used for background checks, and centralized records of mental health prohibitions were almost nonexistent. As a result, a large number of people likely passed their background checks even in cases where, according to law, they should have been prohibited from purchasing a firearm. This remains a serious problem today; mass shootings have resulted from prohibited persons passing background checks and purchasing firearms.”

Wintemute notes that the quality and completeness of the records upon which background checks are completed has improved significantly since 2000 and studies of the more rigorous permit-to-purchase laws show a clear benefit on reducing firearm mortality by as much as 40 percent for homicides and 16 percent for suicides.

Importantly, the Connecticut and Missouri statutes associated with beneficial effects on firearm violence incorporated a permit-to-purchase provision. Permit-to-purchase laws require prospective purchasers to obtain a permit from a law enforcement agency, and complete a background check. Straw buyers or others with criminal intent may be less willing to risk law enforcement scrutiny. Permit requirements may also help law-abiding sellers to identify a prohibited or unauthorized buyer.

In separate survey research from VPRP, approximately 15 percent to 20 percent of firearm owners in California reported that their most recent firearm purchases did not involve background checks. Further analysis is in progress; as mentioned, noncompliance with background check requirements may help explain the findings of the current study.

The study’s lead author was Alvaro Castillo-Carniglia, at the time a postdoctoral scholar at VPRP. Other authors include Magdalena Cerdá from the Violence Prevention Research Program at the University of California, Davis, School of Medicine; and Jon S. Vernick, Daniel Webster and Cassandra Crifasi from the Center for Gun Policy and Research at Johns Hopkins Bloomberg School of Public Health.

This study, entitled “California's comprehensive background check and misdemeanor violence prohibition policies and firearm mortality,” was funded by the Joyce Foundation [grant ID 15-36377, Heising-Simons Foundation [grant ID 2016-219], and UCFC, the University of California Firearm Violence Research Center. Castillo-Carniglia and Kagawa were supported by the Robertson Fellowship in Violence Prevention Research. Castillo-Carniglia was also supported by Becas Chile as part of the National Commission for Scientific and Technological Research (CONICYT).

The UC Davis Violence Prevention Research Program (VPRP) is a multi-disciplinary program of research and policy development focused on the causes, consequences and prevention of violence. Studies assess firearm violence and the connections between violence, substance abuse and mental illness. VPRP is home to the University of California Firearm Violence Research Center, which launched in 2017 with a $5 million appropriation from the state of California to fund and conduct leading-edge research on firearm violence and its prevention.